Solid fossil fueled steam generation creates a self-imposed spent fuel ash deposit on the fire side of the pendant tube elements making up the interior configuration of the boiler. This ash build up eventually becomes inhibitive to the heat transfer and draft characteristics necessary to efficiently produce steam generation. Removal of the spent ash deposit from external tube surfaces, in many situations, is very difficult. The degree of difficulty for removing spent fuel deposits depends on the amount, hardness, and location of the deposit, as well as on the bond of the deposit to the pendant tube surface. The more difficult the deposit is to remove, the more down time is required to clean the boilers. The present invention relates to an improved rotary cleaning device for quickly and efficiently removing ash or slag deposits from boiler tubes.